1. Field of the Invention
The present invention relates to a drive mechanism for driving a movable mirror provided in a camera (e.g., an SLR camera), and in particular to a mechanism, provided in association with the drive mechanism, for suppressing bouncing of the movable mirror.
2. Description of the Related Art
In SLR cameras, a movable mirror (quick-return mirror) is provided, which is capable of moving up and down. More specifically, the movable mirror is capable of rotating between a mirror-down state, in which the movable mirror is positioned in a photographing optical path to reflect incident light emanated from an object (object-emanated light) toward a viewfinder optical system, and a mirror-up state, in which the movable mirror is retracted from the photographing optical path to allow the object-emanated light to travel toward a shutter. A movable mirror which is provided with a main mirror, which is for leading object-emanated light to the viewfinder optical system, and a sub-mirror, which is for leading object-emanated light to a distance measuring sensor and a photometering sensor, is known in the art. The sub-mirror is mounted to the back of the main mirror. When the movable mirror is in the mirror-down state, the sub-mirror is positioned in a photographing optical path at a different angle from the main mirror to reflect part of the object-emanated light passing through the main mirror. When the movable mirror is in the mirror-up position, the sub-mirror retracts to the back (underside) of the main mirror from the photographing optical path.
Upon the movable mirror bouncing (vibrating) upon impact against a stopper when performing a mirror-up operation or a mirror-down operation, vibrations of the movable mirror may cause such problems as camera shake and unstable viewfinder images, thereby exerting an adverse influence on observational performance and limitations to continuous shooting performance. Accordingly, various mechanisms for suppressing bouncing of the movable mirror have been proposed (e.g., Japanese Unexamined Patent Publication H09-203972, Japanese Unexamined Patent Publication H09-203973, and Japanese Unexamined Patent Publication No. 2012-63452).
A type of mechanism which makes the movable mirror come into contact with an elastic member and another type of mechanism which makes the movable mirror come into contact with a movable member which is biased to move by a biaser are known in the art as mechanisms for suppressing bouncing of the movable mirror. However, since a high positioning accuracy of the movable mirror is required mainly when the movable mirror is in the mirror-down position, the positioning of the movable mirror is required to be carried out using a special-purpose positioning member and the mirror bounce-suppressing mechanisms need to be constructed so as not to interfere with the positioning of the movable mirror that is carried out using this special positioning member. In other words, the mirror bounce-suppressing mechanisms are not only required to suppress bouncing of the movable mirror when the movable mirror rotates but also required not to interfere with the positioning of the movable mirror upon the movable mirror reaching either rotational limit position (rotating end) thereof, thus tending to be complicated in structure.
To solve these problems, a simple-structured bounce-suppressing mechanism which is equipped with an interference prevention feature with which no influence is exerted on the positioning accuracy of the main mirror, which constitutes a component of the movable mirror, at a rotational limit position thereof has been proposed in Japanese Unexamined Patent Publication No. 2012-63452. However, in the case of a camera in which a main mirror and a sub-mirror constitute a movable mirror (quick-return mirror), it is desirable to securely suppress not only bouncing of the main mirror but also bouncing of the sub-mirror from the viewpoint of improvement in performance. However, if it is attempted to provide the camera with an individual mirror bounce-suppressing mechanism having the aforementioned interference prevention feature for each of the main mirror and the sub-mirror, the structure will become more complicated.